The word 'critical" has three meanings which are dangerous, important, and disapproving. The purpose of this blog is to examine important or over-looked cultural, political, artistic, or historical issues of our time. Also, this blog is intended to be educational.

Monday, May 29, 2017

The Collapse of Arctic Sea Ice And Global Warming

Earth's already-beleaguered
northern icecap suffered another blow in May, 2017, with the early collapse of
a barrier that kept some of Arctic's most durable ice in place.

The ice arch across the Nares Strait, which separates
Greenland from Ellesmere Island in Canada's far northeast, gave way two months
earlier than usual, said
Laurence Dyke, a paleoglaciologist at the Geological Survey of Denmark and
Greenland.

Nares Strait

On May 10, (2017), this arch disintegrated, leaving the oldest
and thickest sea ice in the Arctic vulnerable to being swept south where it
will melt away,
Dyke said. Over the last two weeks, thearea of broken ice has expanded massively
to the north, and lots of Arctic sea ice is flowing southwards through the
Nares Strait.

The channel and the Lincoln
Sea, at the northern tip of Greenland, are normally covered by a sheet of ice
several meters thick until around July, Dyke said. Usually, ice sheets that
cover the strait are anchored to land and don't move, blocking the passage of
sea ice through the strait.

But
as heat-trapping fossil-fuel emissions like carbon dioxide build up in the
atmosphere, the Arctic is warming twice as fast as the rest of the globe. And
this year, land-anchored ice in the strait failed to form amid the record warmth and record low sea
ice coverage recorded across the Arctic. That left only an arch of ice at the
northern end of the strait, where it joined the Lincoln Sea, the structure that gave way earlier this
month.

This is especially important as the Lincoln Sea contains
the last bastion of old, thick multi-year sea ice, Dyke said.

The Nares Strait is the
smaller of two passages that can funnel ice from that area toward the Atlantic.

The Fram Strait, on the east
side of Greenland, carries significantly
more, said Twila Moon, a glaciologist at the National Snow and Ice Data
Center in Colorado. But every little bit
counts, said Dyke. And the loss of multi-year ice is already a chronic
problem in the Arctic. It forms the heart of next year's sea ice
and provides habitat for whales, seals, and birds.

It's also playing a role to reduce the amount of heat the
ocean can take in during the summer, Moon said. If less ice is floating on the
surface of the Arctic ocean, the dark-colored sea will absorb more of the Sun's
energy - and of course, more heat in the
ocean reduces our sea icefurther,
and we get a runaway effect. Each of these small events adds up, and they're
not good news, she added.

This year's event isn't
unprecedented: Something similar happened in
2007. But when that occurred,
"that led to the largest flux of Arctic Sea ice through Nares Strait in at
least the last fifteen years, Dyke said. Multi-year ice has been steadily declining over the last two decades,
and this early break-up will surely destroy another large portion of it, he
added.

Since
sea ice is floating in water already, its melting doesn't add to sea-level rise
which a recent study suggests has accelerated dramatically since the
1990s. But the warming of the surrounding oceans is already starting to eat
away at the miles of ice that cover Greenland.

Dykes was part of a 2015
expedition to study the Greenland's massive Petermann Glacier, which overlooks
the Nares Strait, and said that the loss of sea ice is starting to affect that
structure.

Petermann Glacier

Sea
ice buttresses the glacier, keeping it from breaking apart. And, there's some
evidence that less sea ice may result in warmer water making contact with the
edges of the ice sheet, further eating away at it. In the last decade, the
glacier has seen two calving events in which Manhattan-sized chunks of ice
broke off into the ocean, and scientists are watching a new crack that has emerged this
spring.

You can think a bit about it as a canary in a coal mine, Dyke said. It's almost the most northerlyglacier in the whole of Greenland, so if
there are changes happening up there, you can be sure that the rest of
Greenland is feeling those effects as well.